This invention relates to a mixing device and method. More particularly, but not by way of limitation, this invention relates to a mixing device for mixing a material and eliminating entrained air while the material is being mixed.
Mixing devices for materials are well known in the art. For instance, in the oil and gas drilling industry, hoppers are used to transport, mix and blend drilling fluids, sometimes referred to as drilling mud. Also, the oil and gas industry has used hoppers to transport, mix and blend cement. These materials being mixed are generally bulky, dry, granular and high density.
As will be appreciated by those of ordinary skill in the art, the materials will be blended in order to reach a consistency of composition and/or consistency of desired density. These parameters are often critical in order to obtain desired results of the ultimate use of the materials. Additionally, the final composition may be critically important in relation to safety of personnel and the environment. Thus, the proper and thorough mixing of these materials is very important.
The components used in drilling fluids may be barite and/or bentonite and/or attapulgite clay, for instance. Barite and cement have a high density and are bulk material. Bentonite, clay and lost circulation material are low density and in and clay have and are bulk material. Generally, a Portland cement is used in the form of finely divided, gray powder composed of lime, alumina, silica, and iron oxide as tetra calcium alumino ferrate. During the process of preparing these types of materials for use, the operator will mix the materials with other components or ingredients, such as water. A problem encountered when mixing with prior art hopper systems is the material being feed down the hopper may contain air and/or entrain air. This air adversely effects the quality of the final product. Another problem with prior art mixing devices includes the clogging of the jets used in the mixing chamber.
Therefore, there is a need for a mixing device that will eliminate air from the material being mixed. Also, there is a need for an apparatus and method for mixing high and low density materials. There is also a need for an apparatus and method that quickly and efficiently mixes high and low density materials.
A product mixing apparatus is disclosed. In one embodiment, the apparatus comprises a hopper containing the product, with the hopper having a throat section extending therefrom. The hopper has a first injection means for injecting a solution into the hopper. The apparatus further contains a mixing chamber connected with the throat section, with the mixing chamber containing a second injection means for injecting the solution into the mixing chamber and mixing the product with the solution to form a slurry. A liquid barrier line in fluid communication with the throat section, with the liquid barrier line capable of delivering a liquid into the inner diameter of the throat section. An exit line extending from the mixing chamber in order to withdraw the slurry may also be included.
In one embodiment, the first injection means contains a nozzle member positioned in a downward direction, with the nozzle member being positioned so as to deliver the solution into the hopper and throat section under a pressure. In another embodiment, the first injection means may contain a plurality of nozzles positioned about the inner diameter of the hopper, the plurality of nozzles being positioned in a downward fashion. In yet another embodiment, the first injection means contains a circular injection member positioned about the inner diameter of the hopper, with the circular injection member containing a plurality of nozzles.
In another embodiment, the second injection means is a jet nozzle, with the jet nozzle being connected to a pump member for delivering the solution under a pressure, which in the preferred embodiment is a pressure equal to or less than 200 psi. In yet another embodiment, the second injection means may include a first jet nozzle and a second jet nozzle, with the first and second jet nozzle being connected to a pump member for delivering the solution under a low pressure. In this embodiment, the apparatus further comprises a second exit line associated with the second jet nozzle, and a ceramic plate positioned between the first and second jet nozzle, with the ceramic plate acting to channel the stream from the first jet nozzle to the first exit line and channel the stream from the second jet nozzle to the second exit line. The apparatus may also include a directional cleaning nozzle positioned in the throat section, with the directional cleaning nozzle being angled to deliver the solution to the jet nozzles.
Also disclosed is a method of mixing a material. The material may be a high or low density bulk material or a fluid. The method generally comprises placing the material into a hopper, with the hopper having a throat section and a mixing chamber extending therefrom. The method then includes descending the material into the hopper and injecting a solution into the hopper. The solution may be water or any other solution used to treat or combine with the material. A liquid is communicated into the throat section just above the mixing chamber so that a barrier of liquid is kept above the mixing chamber jets that keeps air from mixing in the fluid.
The method may further include channeling the bulk material and the solution via the throat into the mixing chamber and injecting another solution into the mixing chamber with an injection means to form a slurry. Next, the slurry is exited from the mixing chamber.
In one embodiment, the step of injecting the solution includes injecting the fluid into a plurality of nozzles positioned within an inner diameter of the throat section. Additionally, the step of injecting the solution may be performed with a pump means for pumping the solution into the throat section. In yet another embodiment, the step of injecting the drilling fluid comprises a first nozzle and a second nozzle, both positioned within the mixing chamber, and a ceramic plate positioned between the first nozzle and the second nozzle, and wherein the step of exiting the slurry includes exiting from a first and second outlet line.
An advantage of the present invention includes reducing trapped and entrained air from the material that is being mixed. Another advantage is that the apparatus and method may be used with bulk materials such as drilling mud, loss circulation material and cement. Alternatively, the apparatus and method may be used to mix liquids.
Yet another advantage is that the novel invention aids in mixing high and low density products, and therefore, the product is easier to pump. The invention works particularly well with low density products. Still yet another advantage is that the mixing will improve presolubilization of dry products. Another advantage is that the slurry will be of a more uniform consistency, and therefore, it will make the slurry more predictable and safer in its ultimate use.
A feature is that the liquid barrier line provides enough of a liquid volume above the jets in the mixing chamber to create a barrier of liquid above this jet thus keeping the air out of the mixing chamber. Another feature of the liquid barrier line is that it is large enough to allow a sufficient amount of fluid from the tank to gravity feed into the throat above the mixing chamber thereby providing a continuous liquid column above the mixing chamber jets. Another feature of the present invention is the venturi effect created by the jets in the throat and mixing chamber. Another feature is the nozzle in the throat section introducing a solution under pressure. Yet another feature is the implementation of two jet nozzles within the mixing chamber. Still yet another feature is the use of a plate to direct the output from the jet nozzles to the output lines. Another feature is that multiple nozzles may be situated about the throat. Yet another feature is that a cleaning nozzle may be used for cleaning the mixing chamber jets.